This invention relates to the field of automatic analytical instruments. More particularly, the invention is concerned with automatic chemistry analyzer instruments for clinical use. In such instruments, there are sample carousels and sample handling systems.
Different clinical analyzers for automatic chemistry analysis are known. One particular kind uses a plurality of individual analysis modules having open reaction cups. An automated sample probe withdraws sample fluid from samples in containers carried on a carousel. Selected volumes of the sample are distributed to analysis module cups in accordance with the tests selected by the instrument operator.
A different kind of analyzer uses a flow cell through which diluent and reagent flows together with samples for determination of electrolytes in the fluid sample. Usually, four electrolytes, namely, sodium, potassium, chloride, and CO.sub.2 are measured. In such analyzers, a pick-up probe extends vertically through a shear valve to aspirate the fluid sample from a sample cup aligned with the probe. The probe is withdrawn into the valve and the lower portion of the valve closes. Diluent from a diluent source flows into the valve, is mixed with the sample from the probe and flows to a flow analysis module.
Each of these different kind of analyzers have their unique advantages in analysis of fluid samples. The flow cell analyzer provides simplified fluid handling and minimizing reagent consumption.
The present invention is particularly concerned with flow cell analyzer systems and means for improving the operation, movement, and visibility of the various components and fluids. One of the difficulties in flow cell analyzers is the problem in monitoring the flow stream through the flow cell. Moreover, the flow cell is often located in a manner that is not easily physically accessible or visible which causes difficulty in maintenance and troubleshooting procedures which increases costs of operation. Moreover, another difficulty associated with the flow cell is the difficulty of injecting sample from the sample cup into an injection cell and draining fluid from the flow cell and subsequently from the system. Multiple pumps and wash facilities are often needed to ensure effective injection and drainage. These considerations increase costs and maintenance requirements.
A further problem arises from the arrangement for injecting reagents into the flow cell. Prior art methods include the use of peristaltic/multistage pumps related so as to develop different pumping ratios. It has been relatively difficult to ensure accurate tolerances with the relative ratios of fluids to be pumped in the system.
Other problems which arise are due to electrical noise within the system, and the need to minimize this noise to ensure accurate results. Different techniques have been employed, including a strategic location of the ground for the system.
Many other characteristics exist in the prior art systems which are in need of improvement. These include the sample handling mechanism, means for moving samples from sample reaction cups to an injection cell, means for and the number and nature of the motive means and the electronic operations. All of these characteristics in the prior art have various limitations.